Let's first introduce the common drilling holes in PCB: through holes, blind holes and buried holes. The meaning and characteristics of these three holes

Let's first introduce the common drilling holes in PCB: through holes, blind holes and buried holes. The meaning and characteristics of these three holes

by：Rigao 2020-01-20

Through Hole (VIA)
This is a common hole used to conduct or connect copper foil circuits between conductive patterns in different layers of circuit boards. For example (Such as blind holes, buried holes)
However, it is not possible to insert copper-plated holes for component legs or other reinforcing materials.
Because PCB is formed by stacking and accumulating many copper foil layers, each layer of copper foil will be covered with an insulating layer, so that the copper foil layers cannot communicate with each other, the link of its signal depends on the through hole (via)So there is the title of Chinese guide through the hole.
Features are: in order to meet the needs of customers, the through hole of the circuit board must be plugged, thus in changing the traditional aluminum plug hole Technology, white mesh is used to complete the solder mask and plug hole of the circuit board surface, make its production stable, quality reliable, and use more perfect.
The through hole mainly plays the role of connecting and conducting circuits to each other. With the rapid development of the electronic industry, higher requirements are put forward for the manufacturing process and surface mount technology of printed circuit boards.
The process of plugging through holes has been applied and the following requirements should be met: 1.
There is copper in the guide hole, and the solder mask can be plugged. 2.
There must be tin and lead in the conduction hole, and there must be a certain thickness requirement (4um)
No solder resist ink is allowed to enter the hole, resulting in tin beads in the hole. 3.
The through hole must have a solder resist ink plug hole, which is opaque and must not have tin rings, tin beads, flatness and other requirements.
Blind hole: it is to connect the outermost circuit in the PCB with the adjacent inner layer by plating hole, because the opposite side cannot be seen, so it is called Blind Pass.
At the same time, in order to increase the space utilization between PCB circuit layers, blind holes are applied.
That is, the through hole to one surface of the printed board.
Features: The blind hole is located on the top and bottom surfaces of the circuit board and has a certain depth. It is used for the link between the surface line and the inner line below. The depth of the hole usually does not exceed a certain ratio (Aperture).
This kind of manufacturing method requires special attention to the depth of drilling (Z axis)
To be just right, if you don't pay attention, it will cause difficulty in electroplating in the hole, so there is almost no factory use. You can also drill the hole when the circuit layer that needs to be connected in advance is in the individual circuit layer, finally, it is glued together, but it needs more precise positioning and alignment devices.
Buried holes are links between layers of any circuit inside the PCB but are not conducted to the outer layer, which also means through holes that do not extend to the surface of the circuit board.
Features: in this process, the method of drilling after bonding cannot be used. Drilling must be carried out at the time of individual circuit layers, and electroplating treatment should be carried out after the inner layer is partially bonded, finally, it can be fully bonded, which is more expensive than the original through hole and blind hole, so the price is also the most expensive.
This process is usually only used on high-density circuit boards to increase the usable space of other circuit layers. In PCB production process, drilling is very important and should not be careless.
Because drilling is to drill the required vias on the copper clad laminate to provide electrical connection and fix the function of the device.
If the operation is improper, there is a problem in the process of passing through the hole. The device cannot be fixed on the circuit board. If it is light, it will affect the use. If it is heavy, the whole board will be scrapped, therefore, the drilling process is very important.